We are measuring baroreflex sensitivity in essential hypertension using several measurement techniques, to determine whether the techniques agree with each other, whether baroreflex sensitivity is abnormal in essential hypertension, and whether baroreflex abnormalities are related to pressor responsiveness and plasma catetholamines. We also are investigating the effects of cholinergic blockade on pressure and depressor responses, whether baroreflex abnormalities occur in normotensives with a strong family history of hypertension, and the applicability of a mathematical model of the brachial arterial system to explain defective moddulation of the brachial arterial dicrotic wave in young hypertensives in the baroreflex study.